The union says the mandate covers almost all of its 57 locals, in 53 school districts across the province.

CUPE BC K-12 spokesman Colin Pawson says members have not had a wage increase for more than four years and the union is hoping for funded settlements similar to those for other public-sector employees.

Legislation in 2012 ended a three-day walkout and bitter work-to-rule campaign by public school teachers.

The BC Teachers' Federation signed a one-year contract that expired last month, but any new negotiations are already strained as the Liberal government aims for a 10-year deal.